Jellyfish: Conditions are ripe in Virginia

A Hampton Roads native, Julie McDade knows not to let her kids dash into the water of local beaches.

She walks out with them, alert for the scorn of summer swimmers: jellyfish.

"We were wondering if they were going to be out there today," the Portsmouth resident said Friday at Huntington Beach in Newport News. "We went out pretty far, but there's nothing."

For now.

Jellyfish season, which spans from May to October, is well under way and beachgoers across Virginia have reported seeing the gelatinous creatures near shore.

Like mosquitoes, the weather helps determine how many appear in the Chesapeake Bay and Atlantic Ocean. Hot and dry conditions raise the temperature and salinity of the water, which, in turn, creates an ideal breeding ground.

The region's most common jellyfish is the sea nettle, a white, umbrella-shaped orb that grows to about four inches in diameter. With up to 24 tentacles, it's also the one most responsible for stinging swimmers.

The sting, which produces painful rashes and welts but is rarely life-threatening, is essentially a poison dart that sea nettles fire from their tentacles.

There is little evidence that sea nettles seek human flesh. Most are trying to protect themselves against a perceived threat, Deborah Steinberg, a VIMS professor, told the Daily Press last year.

Brainless, eyeless and without a spinal cord, sea nettles and other jellyfish are among the more primitive forms of life in the bay and ocean. They use their tentacles to capture and paralyze their prey, which consists of small fish, shrimp and other jellyfish.

Not strong swimmers, they travel by drifting in the bay's currents and propelling themselves forward by contracting their bells.

"The jellyfish have no idea where they are going," said George Mathews, curatorial director of the Virginia Living Museum in Newport News.

Sea nettles are typically found in brackish water that is 78 degrees to 86 degrees, according to VIMS. The National Oceanic and Atmospheric Administration has an Internet page that predicts where sea nettles are based on those preferences. (You'll find a link at chesapeakebay.noaa.gov.)

According to Friday's forecast, swarms surrounded Virginia's Northern Neck, particularly at the mouths of the Potomac and Rappahannock rivers. There were additional swarms at the James and York rivers.

In addition to sea nettles, beachgoers are likely to spot moon jellyfish, which grow to about 12 inches in diameter and resemble a dinner plate. Virginia also has lion's mane jellyfish, also known as winter jellyfish, that typically appear from November to May.

Neither are likely to sting swimmers, Mathews said. The same can't be said for sea nettles, though there are measures to avoid them.

As a young marine biologist, before wetsuits were readily available, Mathews and colleagues would wear pantyhose while in the water.

"They were cool and comfortable," he said, "but we got some funny looks."